The present invention concerns filter cleaning mechanisms suitable for use in hand-holdable vacuum cleaners. Such vacuum cleaners are well known for collecting dust and dirt, although wet-and-dry variants which can additionally collect liquids are also known. Typically, hand-holdable vacuum cleaners are intended for use in a domestic environment, although they also find uses in other environments, such as worksites. Generally, they are electrically powered and therefore comprise an electric motor, an electrical on/off switch for a user to operate said motor, a fan connected to an output shaft of said motor, an inlet for dirty air, an outlet for clean air and a collection chamber for dust, dirt and possibly also liquids. Electrical power for the motor may be provided by a source of mains electricity, in which case the vacuum cleaner will further comprise an electrical power cable, by a removable and replaceable battery pack, or by one or more in-built rechargeable cells, in which case the vacuum cleaner will further comprise some means, such as a jack plug, for connecting the vacuum cleaner to a recharging unit. When the vacuum cleaner is provided with electrical power from one of these sources and the on/off switch is set to the “on” position, the electric motor drives the fan to draw dirty air along an airflow pathway in through the dirty air inlet, via the collection chamber to the clean air outlet.